The cast of WGN America’s period drama “Manhattan” continues to grow, as “Dollhouse” alum Olivia Williams has been tapped to join the new tale about the making of the atomic bomb.

Williams, whose previous credits also include films “The Sixth Sense” and “Rushmore,” will play Liza Winter, a botanist with a complicated past. Other cast members include John Benjamin Hickey, Daniel Stern, Harry Lloyd, Ashley Zukerman, Rachel Brosnahan, Christopher Denham and Katja Herbers.

“Manhattan,” which is scheduled to premiere in July, is a production of Skydance Television, Tribune Studios and Lionsgate Television. It’s written and created by “Masters of Sex’s” Sam Shaw, who is exec producing with David Ellison, Dana Goldberg and Marcy Ross. “The West Wing’s” Thomas Schlamme is directing and exec producing under his Shoe Money Productions banner.